Topic 5.3 - Energy and Ecosystems Flashcards
(22 cards)
There are three types of sampling, what are they?
Random Sampling, Transect and Mark, Release, Recapture.
When is Random Sampling used?
To find the number of ‘non-motile’ organisms in a habitat.
Give an example of when you could use Random Sampling.
Number of daisies in a field.
What equipment is needed for Random Sampling?
2 measuring tapes, a quadrat and a random number table.
How is human bias avoided for random sampling?
Place the tape measures along the sides of the sample area forming a grid. Using the random number table, obtain co-ordinates for the placement of the quadrat on the gird. Bias is avoided as the co-ordinates are from the random number table.
How are the measurements made accurately in random sampling?
A suitable quadrat must be used. The top left rule has to be used.
How is reliability ensured in random sampling?
The quadrat must be placed in 20 different co-ordinates of the sample area. Then a running mean is calculated to decide if more data is required.
When is the Transect technique used?
The transect is used to investigate a gradual change in the habitat.
Give an example of when a transect can be used.
To determine whether the distribution of dandelions increased with distance from the road.
What equipment is needed for a Transect?
A suitable quadrat, 2 measuring tapes and a random number table.
How is human bias avoided for the transect?
Using a random number table to obtain the co-ordinates for the second tape measures placement on the first. This is a form of systematic sampling, eg place the quadrat every 5m. Use a random number table for systematic sampling bit.
How are measurements made accurately for the transect?
Using a suitable quadrat and the top-left rule.
How is reliability ensured in the transect?
Calculate a mean of the parallel transects.
Do you have to state the direction of the transect?
YES!
When is the Mark, Release, Recapture method used?
To estimate the number of motile organisms in a habitat.
What equipment is used for Mark, Release, Recapture?
Many traps, 2 measuring tapes, random number table.
How is human bias avoided in the Mark, Release, Recapture method?
There is a random placement of traps. There is also random co-ordinates/systematic sampling.
How are the measurements of the Mark, Release, Recapture method made accurately?
The mark must not change behaviour/ lost between sampling times. The mark must not change predation chance.
How is reliability ensured?
Use as many traps as possible, e.g. 20.
What is the formula for the Mark, Release, Recapture method?
N1/N = N3/N2 (Lincoln index)
What does each variable of the Lincoln Index represent?
N= Population
N1= First Sample
N2= Second sample
N3= Recaptured
Give an example of the Mark, Release, Recapture method.
Estimate the size of the population of woodlice in a house.
